The consumer group has branded the creams as “don’t buys” in its investigation, which used British Standard tests to check 15 products with an SPF (sun protection factor) of 30 – a bestseller in the UK.

A second round of testing produced the same results, Which? said.

The sunscreens tested are designed to protect against two types of ultraviolet radiation: UVA and UVB.

Both types have been linked to skin cancer, although UVB is the main cause of sunburn and UVA has been linked to premature ageing of the skin.

EU recommendations say sun creams should offer a UVA protection factor that is a third of their SPF value.

Which? said Malibu Protective Lotion SPF30 200ml was the only sun cream that also failed the UVA protection tests with a UVA protection factor below 10.

The study also found that the more expensive creams did not guarantee better protection.

Calypso Sun Lotion SPF30 250ml was the cheapest product on test, costing £1.20 per 100ml, and passed both British Standard tests.

Which? executive director Richard Lloyd said: “With thousands of cases of skin cancer diagnosed every year, it’s vital you can trust a sun cream to provide the protection it claims.

“We’ve found three products that failed the strict British Standard tests and we want to see manufacturers doing much more to make sure their sun creams live up to the claims on the packaging.”

Malibu said: “We stand by our testing and are willing to have our formula tested again by any reputable UK testing house. We have nothing to hide. Our files are open for any legitimate person to come and examine.”

Hawaiian Tropic told Which? that it only marketed products that met the label SPF claim, and said all its products were rigorously tested at an independent, well-qualified laboratory.

It said it was confident that its test results indicated that Hawaiian Tropic Satin Protection SPF30 exceeded the label claim and EU requirements.

Piz Buin told the consumer group that all of its products were assessed for safety and efficacy in compliance with EU regulations.

It said the SPF labelling of its products was based on a package of information that considered formulation as well as rigorous testing, adding that it was confident that Piz Buin Ultra Light Dry Touch Sun Fluid provided SPF30 protection and noted that variability in test results between laboratories was associated with the SPF test.